forward07

R&D activities was initiated at RRL Branch, Itanagar of Arunachal Pradesh with the objective to develop a better strain of lemon grass having high biomass, oil and citral content. Accordingly, a new clone of lemongrass was developed which was designated as BLI-1. This strain recorded very good herb yield ( ca 35 to 39 t/ha) and 0.8 to 1.12% essential oil on FWB. The major constituents of the oil were geraniol (30.5 to 30.8%), citronellol (24.1 to 24.3%), geranial (13.0 to 13.6%) and neral (10.1 to 10.3%). As per BIS specification the minimum requirement of citral content should be 75% in lemongrass oil. An attempt was made to develop a yet high biomass, oil and citral yielding clone of lemon grass. A survey was made and SD-68 strain of Lemongrass (oil content 0.25-0.30%, citral 84-86%) developed by CIMAP was choosen as one of the parents for crossing with BLI-1. Study of floral biology revealed marked variation in shape and size of pollen grain between the two strains. The average pollen size of SD-68 is 33.2 u) (range 33.1 to 36.4 u) as against 26.4 m (range 18.3 to 31.2 m) in BLI-1 strain. In addition in vitro germination of pollen of SD -68 recorded 48% germination compared to no germination in case of BLI-1 strain. Stigmatic receptivity was also very hgh (62%) in case of BLI-1, which is poor in SD-68. Considering this it was decided to take up artificial breeding work by emasculation method. The collected data revealed that the BLI-2 is superior in all respects so far as the biomass yield, oil and citral content and yield of oil as well as citral per unit area were concerned. Further, this new strain maintained it consistency in respect of oil and citral content throughout the year with not much variation. Cymbopogon is an important genus of aromatic grasses with about 120 species having varied combination of terpenes and non-terpenic phenolic compounds. Lemongrass oil is used in perfumery, cosmetic and pharmaceutical industries. The oil, obtained from the fresh herb of Cymbopogon flexuosus valued for citral content has good demand both in the domestic as well as in the international market. In the recent past India was the major producer and exporter of lemon grass oil which, however, has declined considerably due to low production and competition from other countries. The reason for low production of lemongass oil in India was due to non-availability of strain having the potential for high biomass yield, oil and citral content.

In commerce, Cinnamomum verum and C. cassia are used as sources of cinnamon spice. Instead of these species, the laboratory identified a bushy shrub species (Fig. 1) viz. Cinnamomum pauciflorum Nees (Lauraceae) growing sporadically in Khasi and Jaintia hills. The bark (Fig. 2) and leaves (Fig. 3) of the plant possesses an odour and taste similar to that of commercial Cinnamon spice (Cinnamomum verum). The shade dry leaves contain 4% (w/w) essential oil. Twenty-five components representing 98.8% of the total oil were identified. Cinnamaldehyde (E)-cinnamaldehyde) was the major component which alone constituted 89.85 of the total oil.

Cinnamomum pauciflorum -

live plant sps.

C. pauciflorum - stem bark processed locally

in the form of quill for local market

Cinnamomum pauciflorum -

leaves

Other components above 1% concentration in the oil are linalool (2.60, (Z)-cinnamaldehyde (1.2%) and a-pinene (1.0). The result was also compared with the composition of essential oils reported for the existing cinnamon sources of commerce viz. Cinnamomum verum stem bark and Cinnamomum cassia bark and leaves. The study revealed that the composition of C. pauciflorum leaf essential oil was differed from the essential oils of existing cinnamon sources (C. verum & C. cassia) by the presence of three components (one aldehyde and two diterpenes) constituting only 0.3% of the total oil. The yield of essential oil by C. pauciflorum leaf was also higher than that of these sources.

(i) An efficient in-vitro regeneration protocol for Homolomena aromatica Schott an aromatic medicinal herb (Linalool source) was achieved. In-vitro regeneration plants showed 90% survivality in field condition. Present market price of this oil is ranged from Rs.4000- 5000/kg.

(ii) In-vitro multiplication technique of an endangered Vanda species i.e. Vanda coerulea (Blue Vanda)acclaimed as the `Queen of the Vandas’ was developed. Natural germination of this orchid is very poor about 5%. Earlier worker reported 90% in-vitro germination after 8 month of culture period, but in this present case 90% germination achieved within 3 month of incubation period. In-vitro regenerated plant went through hardening followed by their eco-rehabilitation, which showed hearlthy growth.

From the study of two years data of Piper longum it was revealed that the plants raised from whole leaf gave highest yield of fruit compared to saplings raised from nodal cuttings.

A two year experiment on spacing cum harvesting of Kaempferia galanga was conducted at NEIST Branch, Itanagar farm. The experiment revealed that harvesting time 18 months with spacing of 20 x 20 cm was the most cost effective. Experiment was also conducted to find out comparative yield performance of Kaempferia galanga using vermi compost. FYM, NPK alone and their combinations for 18 months duration. It was found that vermicompost @ 2 tons/ha recorded highest yield of tube and was the most cost effective and more advantageous than the others.

Information on the usage of 62 plant species represented by 69 prescriptions and 15 broad diseases used by the Deori community of Assam were documented with an objective to review the activity of medicinal plants used in the herbal pharmacopoeia and also to prepare an inventory of plant folk medicines of these people practiced in the region. For each plant species, popular medicinal use, local names, parts used, forms of preparations and applications and ailments treated were documented.

An inventory of 65 plant species indicating positive correlation between their folklore claims and biological activities was prepared. For each plants species described, botanical name, local name(s), part used, folklore claims and biological activities were given. The study not only revealed the authenticity of traditional knowledge of some ethnic people of North East India on utilitarian aspects of these plant species but also indicated the possibility of utilizing them for greater economic benefits.

Evaluation of 20 elite accessions of Jatropha curcas collected from different regions of India are continuing under agro-climatic conditions of Jorhat, Assam; Naharlagun, Arunachal Pradesh and Imphal, Manipur for their yield. Beside this, a total of 166 numbers of native accessions of J. curcas were collected from 21 States of India including seven States of N. E. India. These were planted to observe their performance under agro-climatic condition of N.E India. Native accessions from N E India were found to contain 25.18%-36.83% fatty oil on dry weight basis. Determination of agronomic parameters viz. mode of propagation, spacing, nutrient and pollarding were under study.

Occurrence of leaf spot disease of Jatropha curcas was recorded. From microscopic observation it was found that the mycelium of the fungus was dark brown and septate; conidiophores brown and septate; conidia are dark coloured and slightly beaked with cross and longitudinal septa. From the observations, the pathogen responsible was tentatively identified as Alternaria sp.

The most common weed observed in the Patchouli plantation are - Alternanthera sessile, Cynodon dactylon and Oxalis cornicullata. Co-distillation of fresh Patchouli leaves with weeds at the rate of 0, 5, 10, 15 and 30% yielded 0.70, 0.67, 0.65, 0.50 and 0.43% oil respectively. It was observed that the oil yield decreased gradually with the increase in weed biomass. However, the percentage of patchoulol showed a different behaviour. It decreased at 15% (53.7) and 30%(50.4) and increased at 5% (56.5) and 10%(63.8) treatments. The oil extracted with weed biomass imparts a weedy odour, which may decrease its commercial value.

Callus and cell suspension culture of American ginseng (Panax quinquefolium) was established and four batches of cell suspension were run in Bioreactor system very successfully. Analytical observation through TLC/HPLC of the harvested materials indicated the presence of ginsenosides.

Influence of leaf blight disease on yield of oil and constituents of Java citronella and In-vitro control of the pathogen using essential oils

Leaf blight of Java citronella (Cymbopogon winterianus Jowitt), caused by Curvularia spp. has proposed effect on the quality of oil. The percentage decrease of the major constituents of oil from diseased plants was found to be 52.8, 50.0, 47.1, 46.5, 30.7 and 19.1 for citronellol, linalool, citronellal, citranellyl acetate, geranyl acetate and limonene, respectively compared to healthy plants. The causal organism, Curvularia spp. might have altered the monoterpenoid biosynthesis in the host. The in-vitro fungitoxicity of essential oils of Citrus sinensis (exocarp), Curcuma longa (rhizome) and Elettaria cardamon (seed) against the Curvularia spp. was studied and found to completely inhibit mycelial growth at different concentrations. The fungitoxicity of the oils was unaffected by variation in temperature and prolonged storage.

Feeding and oviposition preference of Helopeltis theivora (Hemiptera : Miridae) on tea in Northeast India

Feeding and oviposition preference of Helopeltis theivora was studied which revealed that insect mostly preferred the second leaf for feeding in comparison to the first and third leaf and stem, while fifth instar nymphs were the most voracious feeder among the different life stages. The insect preferred to oviposit mainly on stem and very few eggs were observed on leaves. The findings were significant as they would help in developing effective control strategies against the insect pest.

Plant extracts and fractions (65 Nos.) were evaluated against tea mosquito bug Helopeltis theivora for long term and short term bioactivities and 6 numbers of further purified fractions were taken up for optimization studies in lower concentration, dose-dependency, persistency and compatibility studies. Results of the studies revealed that one sample had promising prospects for process development.

Introduction of Ganoderma lucidum was taken up. Preparation of spawn was successfully carried out for in-vitro cultivation utilizing different synthetic medium.

Search for chemotypes of Litsea cubeba for high quality essential oil of commercial utility

Identified four chemotypes of Litsea cubeba from North East Indian germplasm. The essential oil of leaves and fruits of these chemotypes are rich in Citral (88.0%), Sabinene(64.0%), Linalool(70.0%) and Citronellal(83.0%). These chemotypes possess greater scope for commercial exploitation. Essential oil of these species could be exploited commercially as alternative source of aroma chemicals.

Assessment of genetic diversity in Zanthoxylum spp. of North East India using PCR based molecular markers
Under a DBT funded project, the samples of different Zanthxylum spp. from Assam,Nagaland,Meghalaya, Manipur & Sikkim were collected to study the genetic diversity among different species and within the species.Two PCR based techniques i.e. RAPD and AFLP were standardized for undertaking the study.

RAPD profiles of some samples of Zanthoxylum acanthopodium

generated using OPA-09 primer.

AFLP profiles of some samples

of Zanthoxylum armatum genotypes

generated using primer combination

E-ACC X M-CTG

Improved biomass production in Machilus bombycina through molecular markers and Plant Growth Promoting Rhizobacteria (PGPR) and their application in muga silk worm culture

More than fifty (75) RAPD primers were tested. Among different primers, 25 primers showing good amplification were used for marker development. Large numbers of amplified bands were obtained. Among these primers, search was on to find unique band for PGPR positive plants. Further work was in progress.

Developments of integrated genetic linkage MAP and marker assisted selection of tea

Tea plant materials were collected for study of resistance to blister blight disease from TRA germplasm bank. Crossed for generation of F1 population were also done using resistance and susceptible genotypes as 2 parents. Work was in progress.

Isolation, Characterization, Functional and molecular properties of bacterial toxin (In vivo studies with the Muga silkworm tissues)

The toxin (protease) released by Pseudomonas aeruginosa strain AC-3, a causual organism of flacherie disease in muga silkworm, Antheraea assama was characterized and its activity against the muga silkworm tissues were assayed. When grown in casein broth macimum protease production occured when the strain was cultivated for 60 hours. The molecular weight of the purified protease was found to be 35 Kda. This partially purified protease reduced the larval survivability and other biochemical changes with respect to the protein profiles in the tissues of the silkworm (silk gland and haemolymph ).

Pathogenic Pseudomonas aeruginosa strain AC-3 maintained on (a)Agar media,

(b) Luria broth, (c) Toxin(Protease), (1) Molecular markers (2) Toxin

Heamolymph was collected from the larvae on 2nd and 3rd day after the infection and pooled in a tube containing a few crystals of phenylthiourea at 4oC by cutting off an abdominal leg. The haemolymph was immediately centrifuged in the cold at 10,000 rpm (rotor head 13 cm) to remove haemocytes. Haemolymph was also collected from control larvae ( sterile saline-injected ) in the same way to study the effect of bacterial infection on protein profile. Comparative protein profile of haemolymph of saline-injected control and infected larvae with p aeruginosa was studied by SDS-PAGE.

SDS-PAGE protein profile of A. assama

haemolymph of saline-injected(control)

and live bacteria-injected (Diseased)

larvae. Lanes 1-3 represent protein

profile of larvae at 0, 1 and 2 days post

saline injection and lanes 4-6 represent

protein profile of larvae at 0, 1 and 2 days

post live bacteria injection

SDS-PAGE of silk gland of (A) diseased

and (B) Control larvae of Muga sikworm,

A assama

Several new protein bands were also observed in the diseased larval tissues and they were found at the low molecular weight region. When the protein profile of the infected larvae was compared to that of the control, more proteins were found to be constitutively synthesized suggesting possible hindered metabolic process during disease development or may be due to proteolytic activity of the bacteria on host proteins. Enhanced biosynthesis of the proteins were observed in live bacteria-injected larvae (induced by infection) as compared to the control were indeed efficient in resisting the biochemical changes caused by live cells of P aeruginosa strain AC-3 which caused death in the non-immunized larvae. This conclusion was drawn based on similarity of the haemolymph protein profile of control and live bacteria-challenged vaccinated larvae. Comparison of haemolymph protein of normal and artificially induced diseased larvae revealed both quantitative and aualitative variations. The appearance of extra bands in all the tissues suggested that these might be the degradation products of the biologically active proteins. This also further supported the hypothesis that the bacterial toxin (protease) released by the P Aeruginosa as a result of infection partially degrades the biologically active and important proteins present in the tissue of the silkworm.

Novel bacterial genus & species documented and introduced into world Microbial Taxonomy in

microbial diversity programme from Garampani hot-spring, Nambar, Golaghat, Assam

Continued search for exploration of microbial diversity prevalent in Indo-Burma hot-zone resulted in the supplementing and documentation of novel bacterial genus and species from Garampani hot-spring of Nambar, Golaghat, Assam. Introduced bacterial genus Aquimonas voraii and species Penibacillus assamensis, Aeromonas sharmana, Flavobacterium indicum isolated from the North East gene pool was a significant contribution into basic Microbial Taxonomy. Further, 10 new 16srRNA sequences were submitted to NCBI database, Bethesda, USA. The work was carried out in collaboration with IMTECH, Chandigarh and IGIB, New Delhi.

NEIST team participating in Microbial diversity programme was maintaining a stock cultures collection of more than 2000 indigenous microbial strains in culture collection centre. These strains were screened under the various ongoing projects in both CSIR Task Force & in-house projects, in search of novel antibiotic, enzymes and for biotransformation potential, especially for development of drug and drug intermediates. All these culture includes bacteria, fungi and actinomycetes along with recent isolates of endophytic strains having pharmaceutical potential.

The three-component one-pot condensation of 6-amino-1,3-dimethylbarbituric acid, an aldehyde and an unactivated cyclic ketone like 4-hydroxy coumarin in the presence of piperidine afforded biologically significant dihydropyrido [2,3-d]pyrimidin-4(3H)-ones and tetracyclic pyrido[2,3-d]pyrimidine derivative in good yields when carried out under microwave irradiation in a solvent free condition.

In recent years attention has been focussed particularly on dihydropyrimidinones (DHPMs), which are an important class of compounds due to their therapeutic and pharmacological properties. They have emerged as integral backbones of several calcium channel blockers (e.g. nifedipine), antihypertensive agents and alpha-1a-antagonists and neuropeptide antagonists. This is an impressive profile that bodes well for the interaction of this heterocyclic building block with a variety of biological targets of interests. Monastrol is the first characterized DHPM which specifically inhibits the mitotic kinesin Eg5 motor protein and can be considered as new lead for the developments of anticancer drugs. Thus synthesis of this heterocyclic nucleus is of continuing interest. A convenient and green method for the one-pot synthesis of various dihydropyrimidinones and thiones using inexpensive ion exchange resin was developed.

Various novel pyrano [2,3-d]pyrimidines and furopyrano [2,3-d]pyrimidines were synthesized in 80-99% yields via a multicomponent domino Knoevenagel/hetero-Diels-Alder reaction of 1,3-dimethyl barbituric acid with an aromatic aldehyde and ethyl vinyl ether/2,3-dihydrofuran in presence of 1 mol% of indium(III) chloride. The reaction also proceeded in aqueous media without using any catalyst, but the yield was comparatively less (65-70%).

The environment-friendly three component condensation of 6-[(dimethylamino) methylene]aminouracil, an aldehyde and ammonium acetate in presence of acetic acid afforded one-pot synthesis of biologically significant novel dihydro-pyrimido [4, 5-d]pyrimidine derivatives in high yields under solvent-free conditions.

The utility of microwave energy in synthetic organic chemistry has been increasingly recognized in recent years. Microwave-promoted solid phase heterogeneous reactions are environmentally benign methodologies having greater selectivity, enhanced reaction rates, producing cleaner products and having manipulative simplicity.

Microwave mediated multi-component reactions constitute a specially attractive synthetic strategy for rapid and efficient library generation due to the fact that products are formed in a single step and the diversity can be achieved simply by varying the reacting components. The efforts were made towards heterosteroid synthsis afforded a facile and rapid synthesis of 4H-thiopyrans from a three-component reaction of an a, b-unsaturated ketone, an alkyne and Lawesson's reagent (LR) under microwave irradiation.

Some novel quinolizine-, indolizine- and pyrido-1,4-oxazine fused quinoline derivatives were synthesized from acetanilides via a three-component reaction in solvent-free condition and by exploring the a-cyclisation of tertiary amine reaction strategy. The formation of the products in the three-component reactions is established by performing the reactions in multiple steps. This cost efficient, environment friendly and operationally very simple protocol for the synthesis of tetracyclic angularly annelated quinolines from easily available starting materials is a valuable addition to quinoline chemistry.

Starting from easily available organic compounds (acetanilides) and by exploring the intramolecular 1,3-dipolar cycloaddition reactions involving nitrone, nitrile oxide and nitrile imine as dipoles, some novel classes of complex quinoline derivatives were prepared. The fused isoxazoles and pyrazoles in the new molecules have rich chemistry because of their ready reductive cleavage and susceptibility to ring transformations. This reaction has opened a convenient route for the synthesis of various heterocycle fused quinoline derivatives by generating different dipoles and dipolarophiles in the quinoline molecule.

Some novel 3-alkylated indoles were synthesized via a three-component reactions in solvent-free conditions. The results demonstrated a novel uncatalysed Michael addition of indoles to an <,b-unsaturated system in a one-pot three-component reaction under solvent-free conditions. The mechanism of the three-component reaction was established by synthesizing the proposed intermediate and by performing the overall transformation in two steps.

Highly efficient and green method for the synthesis of 3,4-dihydropyrimidin-2-ones and

A simple, efficient, mild and green method was developed for the synthesis of 3,4-dihydropyrimidin-2-ones employing dodecyl sulfonic acid as an excellent surfactant type bronsted acid catalyst in aqueous media at room temperature. the catalyst was shown to be equally effective for the synthesis of 1,5-benzodiazepines under the same reaction condition

An efficient and one-pot synthesis of imidazolines and benzimidazoles via anaerobic oxidation

The system, I₂/KI/K₂CO₃/H₂O, oxidizes carbon-nitrogen bonds for the synthesis of imidazolines and benzimidazoles from aldehydes and diamines under anaerobic conditions in water at 90oC with excellent yields. The process is green, mild and inexpensive

Synthetic vanillin is currently manufactured from guaiacol, a petroleum based chemical. Preparation of guaiacol is carried out from phenol in two steps. Phenol itself is prepared from benzene, a carcinogen. Guaiacol is converted to vanillin in more than one step. Another method is vanilling from waste lignins of cellulose industry. But due to improved method of pulping and stringent anti-pollution conditions imposed in pulp industry very little lignin is available for this purpose. Also, such lignins are used as fuel in cellulose industry itself. Therefore, there is a need to prepare vanillin the maximum used food additive from renewable resources. During the period preliminary investigation was carried out to prepare vanillin using hydrogen peroxide as the oxidizing agent from ferulate of lignin of rice straw, an agricultural waste also a renewable resource. The reaction was carried out in water as solvent and completed in three hours of reflux. It was observed that a combination of Mn(II) and Cu(II) worked as a catalyst in generating vanilling ( 8-9 mg/50gms of de-fatted rice straw ) under controlled pH. 2-furfuraldehyde and vanillyl alcohol were also identified in the reaction mixture. On esxtraction of the organics the inorganic catalysts remained in the aqueous part and could be recycled. Although vanillin formed was in low yield, yet the result was significant as that was so far the first success to convert lignin to value-added aromatic aldehyde vanillin using a green oxidizing agent hydrogen peroxide.

Synthesis of polycyclic heterocycles through 1, 3-dipolar cycloaddition reactions of azomethine yields 1,3-dipolar cycloaddition reaction offers a simple means of achieving the synthesis of heterocycles in which azomethine ylides constitute a major part as 1,3-dipole. The potential of these ylides are further explored in the synthesis of complex bicyclic and polycyclic heterocycles. This can be best realised by generating azomethine ylides by sequential intramolecular alkylation and deprotonation. Azomethine ylide generated by prototropic shift would be used which will undergo cycloaddition reaction in an intramolecular way with the dipolarphile appended to the same molecule. This would allow the synthesis of polycyclic heterocycles by a one step process many of which form basic skeleton of natural products. Reaction of sarcosine with glyoxal was studied under hydrated media as a part of the work. The work was funded by DST, New Delhi under WOS-A scheme.

A green approach for oxidation of carbinols to carbonyls using hydrogen peroxide under

Catalytic oxidation of carbinols to carbonyls is a highly desirable functional group transformation reaction. It is generally carried out with toxic oxo chromium(v) reagents, pyridinium chlorochromate, hypochlorites, permanganates, etc. Subsequent developments involved the use of other oxidizing agents activated by different transition metals, heavy metals, halides, hypervalent iodines such as Des-Martin-Periodate. However, these reagents are either toxic or hazardous to handle, sensitive to other susceptible sites apart from the target and in some cases it is cumbersome to recover the catalyst from the products. Hydrogen peroxide is the most desirable oxidizing agent as it is safe to handle industrially and releases water as by-product. The following method was developed for converting carbinols to carbonyls using hydrogen peroxide in presence of sodium tungstate and basic Amberlite IRA-400 resin resulting in 79-96% yield when studied for a range of carbinols.

It was observed that while the reaction did not take place at all in dichloromethane, it gave best yield in acetonitrile at reflux temperature in half the time duration (4-6 hours) compared to water and dichloroethane (8-16) hours). On the other hand, the reaction in ionic liquid 1-butyl-3-methlimidazolium tetrafluoroborate was completed within 7-10 hours at 50oC with 75-83% yield.

Synthesis of ultrahigh molecular weight styrene maleic anhydride (St-MA) copolymers by UV irradiation which was till now obtainable through process involving gama-ray irradiation. An ultrahigh molecular weight St-MA copolymer exhibits desirable thermal and pH responsive properties. The novel polymer can be potentially useful forbiomedical application and membrane fabrication.

The Golden Triangle Partnership project was developed to set up an integrated technology mission for the development of Ayurveda and traditional medical knowledge based on synchronized working of modern medicine, traditional medicine and moder science. Department of AYUSH, CSIR and ICMR are the three vertices of the triangle which decided to work together to achieve safe, effective and standardized classical Ayurvedic products for the identified disease conditions and to develop new Ayurvedic and herbal products effective in disease conditions of national/global importance. It was also decided to utilize appropriate technologies to develop single and poly-herbal-mineral products and to develop products, which have IPR potentials. Under the project, the laboratory was to standardize selected medicinal plants/herbs and formulated drugs using bioactive/chemical marker technique. Work on nine medicinal plant parts and one formulation was completed. Markers for these plants were determined and their presence in the plant parts as well as in the formulation were confirmed through HPTLC, LC-MS and HPLC technique.

The manufacture of single isomer product has become an important growth area of the pharmaceutical industry. Synthesis of a range of chiral pharmaceuticals involve the formation of epoxide intermediates. It was planned to prepare certain chirally pure epoxides directly from an olefin by treatment with hydrogen peroxide. The strategy is to use urea-hydrogen peroxide adduct in presence of chiral acid such as (S) or (R)-2-methylbutyric acid and/or (S)-proline, under the catalytic influence of lipase in presence of a suitable solvent. The work would lead to preparation of macrolide antibiotics methymycin, erythromycin and a commercially important pharmaceutical R(-) denopamine used against congestive heart attack. For the work syrene was selected as a model substrate and afterwards extended to other substrates. The investigation showed that with urea-hydrogen peroxide (UHP) adduct, S-2-methyl butyric acid or L-proline in presence of CAL-B (Novozyme-[435]) in different hydrophoebic solvents for several hours resulted in low yield of epoxide (<8%) and was accompanied by 1-2% a-hydroxy phenyl acetaldehyde. L-Proline was then protected in its N-terminal end with bulky 2,4-dinitrophenyl group. Using this N-protected acid the yield increased to 70-80% ( S-epoxide, e.e. 45-83%). Investigation of the reaction under microwave condition was in progress.

Rice is a staple food in many parts of India. Assessment of nutraceutical components, extraction and formulation of the same for health benefits are very important. Therefore, a project was undertaken for the study with the fund extended by the DBT, New Delhi. The R&D was in progress with some specific varieties of rice in the North East India. Initially, anthocyanin and arabinoxylan were taken up as target molecules.

Development of enantio-selective membranes from chiral polymers

R&D work on permeation of enatioselective membrane for resolution of some pharmaceutically important amino acids with good separation factor was done in the laboratory. Based on the results, structure-activity relationship could be made to correlate separation selectivity and permeation rate with molecular structure in terms of hydrophobicity of the amino acids. R&D work on resolution of racemic alcohols was also conducted with good result. Based on experiance of such work, further work for preparation of enantioselective membrane from chiral polymers was carried out. The enantio selective behaviour of the membrane would be studied for some therapeutically important racemic compounds such as trans sobrerol, sulbutamol, captapril, sulmeterol, etc. The R&D was intended to provide an efficient and cost effective method of separation of therapeutically important recemic compounds.

Structural and thermal behavior of comb-like polymer Having n-octadecyl side chains

The cocrystallization behaviour of poly(n-octadecyl methacrylate) (POMA) and its blends with corresponding fatty acid (n-octadecanoic acid) (C18) was explored by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies. The DSC curves for blended samples of POMA with C18 showed the characteristic melting endotherms that corresponded to the melting of the cystallites. The existence of hexagonally packed crystalline lattice is confirmed from the X-ray diffraction studies. Thermal degradation of the polymer and its blend proceeds in a one-step reaction. (© 2007 Wiley Periodicals, Inc. PJ Saikia, and SD Baruah, J. Appl Polym. Sci., 104, 1226-1231, 2007.)

Radical copolymerization of dialkyl fumarate: synthesis, characterization and thermal behaviour

The free radical copolymerization of di(n-alkyl) fumarate bearing C22 alkyl group with vinyl acetate and n-alkyl (meth)acrylates was investigated in toluene at 70 oC. 1H NMR and carbon analysis was used to determine the copolymer compositions. The reactivity ratios of monomer for high conversion polymerization were calculated by conversion extension Kelen-Tudos method. Gel permeation chromatography was used to determine the molecular weights and polydispersity indexes. In order to determine the stability of polymers against thermal degradation, the melting endotherms and thermal stabilities of copolymers were investigated by differential scanning calorimetry and thermogravimetric analysis techniques. The degradation kinetics of the copolymer systems were also investigated with several thermogravimetric analysis models. (Proceedings of MACRO 2006, 9th National Conference on Polymers for Advanced Technologies, NCL-Pune, December 17-20, 2006).

The NE coals, coal fines and non-caking coals cannot be utilized as an energy source in the domestic sector, because of its high volatile and sulphur contents. The briquetting or nodulization followed by carbonization was found suitable for retention of sulphur, reduction of volatiles and increase in stength with good heat value with adequate strength. The process developed was demonstrated

Gainful utilization of the coals of Nagaland and other non-caking coals were tried. A process was developed for manufacture of coke breeze from Konya coals ( Tuensung District ) from Nagaland. The blending of these highly swelling coals with other carbon sources showed positive results which might form cokes of desired quality. The process would help in gainful utilization of Nagaland coals.

Jigging of Assam coal from Tikak Colliery (-10 +6.3 and -6.3 + 4.0 mm fraction) was carried out using plain water as well as additive at a dose of 0.05 % at pH 8 and 5 respectively. The results showed that additive could remove significant amount of mineral matters (~77 to 89 %) with 73 to 75 % recovery and around 2.26-2.49 % sulphur in the concentrate. Benefit using additive over water washing was marginal.

In situ generation of stabilized metal nanoparticles in interlamellar spacing and on mesoporous

Nanoscience and nanotechnology of metal nanoparticles have become most exciting and forefront area of research in chemistry, physics, engineering and biology. Because of higher surface-to-volume ratio, metal nanoparticles have gained much importance particularly in catalytic applications. Metal nanoparticles supported on microporous/mesoporous acidic oxide matrix are expected to behave very differently from bulk metals and are like to act as bifunctional catalysts (metal + acid function). Metal cluster intercalated in clay and supported on modified clay are unique class of clay-composites which are expected to exhibit high catalytic activities. Intercalation of metal acetate like M(CH3COO)2. ( M= Ni, Co, Zn, Cu, etc.) into Na-Montmorillonite produces intersalated product M(CH3COO)2-M+-Montmorillonite(I) which on reduction by polyols (ethylene glycol) method generates in situ the corresponsing metal clusters in the form Mo-Montmorillonite(II) composite. The deposition of M(CH₃COO)₂ on the micro/mesoporous clay support was carried out by incipient impregnation technique and subsequently dialyzed to obtain composites with the salt loaded clay. The composites are characterized by X-ray diffraction.The supported metal salts were subjected to polyol reduction at ~195 oC. The composites are characterized by X-ray diffraction (XRD) and Transmittance Electron Microscope (TEM) and substantiated by thermal studies. The interlamellar spacing of the layered matrix of the clay and modified clay having micro / mesopores provides space for nanoparticles development and assist in arresting the growth of the particles up to nano-range. The composite II at 50oC shows a basal spacing(d001) of about 16.1 Å which decreased to about 13.2 Å at about 300 oC, indicating Mo metal-nanoparticles of about 3.6 Å dimension in the interlayer spacings of the clay. The TEM study of the composites for example Nio-nanoparticles reveal that most of the metal particles are spherical in shape and fall in the narrow size range of 9-12 nm at lower metal-clay loading (1mmol Ni/g clay), while on increasing the loading to 3 mmol Ni/g of clay the metal particles grow to bigger size and span a wider size range of 10-25 nm. It is interesting to mention here that in some composites an ordered or channeled supported metal nanoparticles are formed. Similarly, mesoporous clay supported Auo-nanoparticles 8-16 mm size) are also synthesized and characterized by TEM.

Synthesis of rhodium(I) complexes of P, N, donor's ligands and their catalytic evaluation: (i) Oxidative addition of different electrophiles with rhodium (I) carbonyl complexes of unsy-mmetrical bis-(phosphine) monoselenide ligands, (ii) Dicarbonylrhodium(I) complexes of functionalized pyridine ligands and their catalytic activities
(i)Dimeric chlorobridge complex [Rh(CO)₂Cl]₂ reacts with two equivalents of a series of unsymmetrical bis-(phosphine) monoselenide ligands, Ph2P(CH2)nP(Se)Ph2 {n=1(a), 2(b), 3(c), 4(d)}to form chelate complex [Rh(CO)Cl(P~Se)](1a) {P~Se = h2-(P, Se) coordinated} and non-chelate complexes [Rh(CO)2Cl(P~Se)] (1b-d) {P~Se=h1-(P) coordinated}. The complexes 1 undergo oxidative addition reactions with different electrophiles such as CH3I, C2H5I, C6H5CH2Cl and I2 to produce Rh(III) complexes of the type [Rh(COR)ClX(P~Se)] {where, R = -C2H5 (2a), X=I; R = -CH2C6H5 (3a), X=Cl}, [Rh(CO)ClI2(P~Se)] (4a),[Rh(CO)(COCH3)ClI(P~Se)] (5b-d),[Rh(CO) (COC2H5)ClI(P~Se)](6b-d), [Rh(CO)(COCH2C6H5)Cl2(P~Se)](7b-d)and [Rh(CO)-ClI2(P~Se)] (8b-d). The kinetic study of the oxidative addition (OA) reactions of the complexes 1 with CH3I and C2H5I reveals single stage kinetics. The rate of OA of the complexes varies with the length of the ligand backbone and follows the order 1a > 1b > 1c > 1d. The CH3I reacts with the different complexes at a rate 10-100 times faster than the C2H5I. The complexes have been characterized by elemental analyses, IR, 1H and 31P NMR spectroscopy. (ii) Reaction of dimeric complexes [Rh(CO)2Cl]2 (1) with pyridine ester ligands methylpicolinate(a), methylnicotinate(b), methylisonicotinate(c), ethylpicolinate(d), ethylnicotinate(e) and ethylisonicotinate(f)in 1:2 molar ratio afforded the complexes of the type [Rh(CO)2ClL](1a-f). The complex 1a-f exhibits two equally intense n(CO) bands in the range 2068-2091 cm-1 indicating cis-disposition of the two terminal carbonyl groups. The complexes 1a and 1d undergo partial decarbonylation reaction in solution to give the corresponding chelated monocarbonyl complexes [Rh(CO)Cl (methylpicolinate)] (1a') and [Rh(CO)-Cl(ethylpicolinate)](1d') respectively. The complexes 1a-f undergo oxidative addition reaction with different types of electrophiles like CH3I, C2H5I, C6H5CH2Cl and I2 to yield [Rh(CO)(COCH3)ClIL] (2a-), [Rh(CO)(COC2H5)ClIL](3a-f), [Rh(CO)(COCH2C6H5)Cl2L](4a-f) and [Rh(CO)Cl-I2L](5a-f) complexes respectively. The complexes have been characterized by elemental analysis, IR and 1H NMR spectroscopy. The kinetic study of the complexes 1a-e with CH3I reveals a two-stage kinetics and in general the latter one is faster than that of the first one, while only single stage kinetics is observed for the complex 1f. The catalytic activity of the complexes [Rh(CO)2ClL] (1) in carbonylation of methanol is higher (TON = 844-1251) than the well known [Rh(CO)2I2]- species (TON=653).

Clays, being naturally occurring aluminosilicates, are readily available and are inexpensive. Montmorillonite clay is a member of dioctahedral Smectite group. Natural Montmorillonite has limited catalytic activity which can be enhanced by acid activation and modification. Several products have been developed by modification of such clay (Indigenous source) exhibiting improved / advanced characteristics (Table below). Such products may exhibit acid site concentration 0.2 – 0.6 mmol/g. Layered / Lamellar structure is maintained to a great extent in products D-1 and D-2. In general, such products may act as Solid Acid Catalysts and Supports for active catalytic and other agents for making synergistic or bi-catalytic activities for a number of reactions (Organic transformation) such as : Friedel-Crafts reactions, Alkylation, Acylation etc. exhibiting high Conversion and high Selectivity.

Products Name	Surface Area(m2/g)	Pore size(Å)	Pore Volume (cm³/g)	Particle Size(?m)
D-1	200-250	1 - 20	0.15	< 2
D-2	250-350	1 - 40	0.25	< 2
D-3	350- 400	1 - 60	0.35	< 2

Kinetics of adsorption of p-hydroxy benzoate and phthalate on hematite-electrolyte interface were investigated at a constant ionic strength, I=5x104 mol dm-3, pH 5 and at three different temperatures. The state of equilibrium for the adsorption of p-hydroxy benzoate onto hematite surfaces was attained at 70 h whereas, it was 30 h for phthalate-hematite system. None of the three kinetics models (Bajpai, pseudo first order and pseudo second order) is applicable in the entire experimental time period, however, the pseudo second order kinetics model is considered to be better than the pseudo first order kinetics model in estimating the equilibration concentration both the p-hydroxy benzoate-hematite and phthalate-hematite systems. The variation of adsorption density of p-hydroxy benzoate and phthalate onto hematite surfaces as a function of concentration of adsorbate was studied over pH range 5-9 at a constant ionic strength, I=5x104 mol dm-3 and at constant temperature. The adsorption isotherms for both the systems were Langmuir in nature and the maximum adsorption density of p-hydroxy benzoate is ~1.5 times more than that of phthalate on hematite at pH 5 and 30 oC in spite of an additional carboxylic group at ortho position in phthalate. This is due to the more surface area coverage by phthalate than that of p-hydroxy benzoate on hematite surface. The activation energy was calculated using Arrhenius equation and the activation energy for adsorption of p-hydroxy benzoate at hematite-electrolyte interface is ~1.8 times more than that of phthalate-hematite system. The negative Gibbs free energy indicates that the adsorption of p-hydroxy benzoate and phthalate on hematite surfaces is favourable. The FTIR spectra of p-hydroxy benzoate and phthalate after adsorption on hematite surfaces were recorded for obtaining the bonding properties of adsorbates. The phenolic nC-O appears at ~271cm-1 after adsorption of p-hydroxy benzoate on hematite surfaces, which shifted by 10 cm-1 to higher frequency region. The phenolic group is not deprotonated and is not participating in the surface complexation. The shifting of the nas(COO-) and ns(COO-) bands and non-dissolution of hematite suggest that the p-hydroxy benzoate and phthalate form outer-sphere surface complex with hematite surfaces in the pH range 5 to 7.

Efficient catalytic carbonylation of methanol by using rhodium(I) carbonyl complexes containing

The complexes [Rh(CO)2ClL](1), where L=2-aminophenol(a), 3-aminophenol(b) and 4-aminophenol(c) were synthesized and characterized by elemental analysis, IR and NMR spectroscopy and found that these ligands coordinated to the metal center through N-donor site. The complexes 1 undergo OA reactions with various alkyl halides (RX) like CH3I, C2H5I and C6H5CH2Cl to produce Rh(III) complexes of the type [Rh(CO)(COR)XClL], where R=-CH3(2), -C2H5(3), X= I; R = C6H5CH2¬ X = Cl (4). The catalytic activity of the complexes 1 in carbonylation of methanol, in general, is higher (TON 1189–1456) than that of the well-known species [Rh(CO)2I2]- (TON 1159).

Dicarbonylrhodium(I) complexes of functionalized pyridine ligands and their catalytic activities

Reaction of dimeric complex [Rh(CO)2Cl]2 (1) with pyridine ester ligands methylpicolinate(a), methylnicotinate(b), methylisonicotinate(c), ethylpicolinate(d), ethylnicotinate(e) and ethylisonicotinate(f) in 1:2 molar ratio afforded the complexes of the type [Rh(CO)2ClL](1a-f). The complexes 1a-f exhibit two equally intense n(CO) bands in the range 2068-2091 cm-1 indicating cis-disposition of the two terminal carbonyl groups. The complexes 1a and 1d undergo partial decarbonylation reaction in solution to give the corresponding chelated monocarbonyl complexes [Rh(CO)Cl (methylpicolinate)] (1a') and [Rh(CO)Cl (ethylpicolinate)](1d') respectively. The complexes 1a-f undergo oxidative addition reaction with different types of electrophiles like CH3I,C2H5I, C6H5CH2Cl and I2 to yield [Rh(CO)(COCH3)ClIL](2a-f), Rh(CO)(COC2H5)ClIL](3a-f), [Rh(CO)(CO-CH2C6H5)Cl2L](4a-f) and [Rh(CO)ClI2L](5a-f) complexes respectively. The complexes have been characterized by elemental analysis, IR and 1H NMR spectroscopy. The kinetic study of the complexes 1a-e with CH3I reveals a two-stage kinetics and in general the latter one is faster than that of the first one, while only a single stage kinetics is observed for the complex 1f. The catalytic activity of the complexes [Rh(CO)2ClL] (1) in carbonylation of methanol is higher (TON= 844 -1251) than the well known [Rh(CO)2I2 species (TON=653)

The bottom-up chemical synthesis approach for the generation of metal nanoparticles with controlled size, shape, composition and physico-chemical properties have gained significant attention in recent years. The small sizes of metal nanoparticles make them attractive due to their higher surface-to-volume ratio and quantum confinement characteristics. The increased catalytic and anti-microbial activities of Ag nanoparticles have aroused much interest. In the present work, Ag nanoparticles have been prepared using heterogeneous nucleation and subsequently stabilized on Na-Montmorillonite (Na-Mont) clay matrix. The Ag(I) ion has been exchanged to varying extents in the interlayer of the clay by using AgNO3 and CH3COOAg as starting materials. The bulkier size of the acetate ion also led to intersalation reaction in the Na-Mont. In-situ reduction of Ag(I) was achieved by refluxing in ethylene glycol at 195oC for about 2 h. The different sizes of intercalated and surface loaded Ag particles were found in the nano-range (Fig. 1). The effects of initial concentration, nature of the starting materials on the size and size distribution of Ag nanoparticles have been studied. The variation in size was observed with change in initial concentration and nature of the Ag compounds. The UV-VIS spectroscopy, X-ray diffraction and Transmission Electron Microscopic Techniques have been used to characterize the Ag nanoparticles-clay composites.

Propensity for the air-water interface and ion pairing in magnesium acetate vs magnesium nitrate solutions

Surface tension of aqueous Mg(OAc)₂ and Mg(NO₃)₂ solutions were measured at 25 ^oC for their propensity for the solution-vapour interface. Molecular dynamics simulations reveal a very different behaviour at the solution-vapour interface of Mg(OAc)₂(aq) and Mg(NO₃)₂(aq). As in the aqueous bulk, there is a strong tendency for formation of contact ion pair and even ion cluster in the former but not in the latter system. Acetate exhibits a strong surface affinity both due to the hydrophobicity of its methyl group and due to polarization interactions. In contrast, hydrophilic and polarizable nitrate shows only a weak propensity for the solution-vapour interface and the Mg2+ is per se strongly repelled from the surface. Simulations are supported by the experimental surface tension of Mg(NO₃)₂(aq), where it increases with concentration as for other inorganic salts. However, in the case of Mg(OAc)₂(aq) the surface tension isotherm exhibits a turnover at ~ 0.5 M after which it starts to decrease, indicating a positive net solute excess in the interfacial layer at higher concentration.

Measured surface tension of

Mg(OAc)₂(aq), Mg(NO₃)₂₍aq)

and MgCl₂(aq) at 289.15 K as

a function of concentration.

A snapshot from simulation

of a slab of 0.5 Mg(NO₃)₂(aq)

Color coding: Mg: green; N,

blue; O, red; H, white.

A snapshot from simulation

of a slab of 0.5 _Mg(NO3)2(aq)

Color coding: Mg: green; C,

cyan; O, red; H, white

Characterization of limestone resources of N E Region for value addition and rational

Beneficiation of limestone from New Umrangshu (North Cachar Hillss, Assam) was investigated by dry and wet grinding followed by size separation. The coarse fraction (-25 mm +18.75 mm) contains maximum amount of CaO (~52%) and minimum amounts of SiO₂ (1.53), Al₂O₃ (0.79%) and Fe₂O₃ (0.68%). The fine fraction (-12.5 mm) contains the minimum amount of CaO (50.92%) and maximum amount of SiO₂ (2.25%), Al₂O₃ (0.93%) and Fe₂O₃ (1.32%). Most of the kaolinite clay mineral concentrate in the fine fraction. The limestone may find use as a fluxing material in metallurgy and raw material for manufacturing lime required in manufacturing of sugar, soda ash, caustic soda, water treatment etc.It is possible to obtain a fraction having more than 54% CaO with low SiO₂ (~0.5%), Al₂O₃ (`0.6%) and Fe₂O₃ (`0.7%) by further grinding the lime stone followed by separation by dispersion-cum-settling technique.The work was funded by Ministry of Mines, New Delhi.

Alkali activated blended cements: Mechanical strength, pore solution composition and zeolite formation

The effect of sodium hydroxide, sodium carbonate, sodium sulphate and sodium silicate on the lime reactivity of metakaolin was investigated as per Indian Standard methods. The hydration products were separated by dispersion cum sedimentation technique and the same were characterized. The strengths of the mortar cubes are affected by the nature and concentration of the alkali/salt. The work was funded by Ministry of Water Resources, Research & Development (R&D) Division, New Delhi.

Evaluation of bench scale conditions of preparation of mixed-metal hydroxide and suitability of it as drilling fluid additive for drilling operations of OIL

The suitability of mixed metal hydroxides prepared by the laboratory was evaluated as viscofier for clay based drilling fluid of OIL using clay supplied by OIL Duliajan. Results obtained so far shows that the less than 1 mm fraction content in clay is extremely important for MMH to work as viscofier. MMH, being an inorganic environmentally benign and economically cheap material is a suitable product for oil industry to use as a viscofier in normal drilling operations. The steps involved in its preparation are not very complex. Therefore, the project on successful completion bears prospect for successful commercialization. The work was funded by Oil India Limited, Duliajan.

Development of Specialty polymers by controlled /living radical polymerization for use in petroleum

The project was aimed at the development of tailor made polymeric additives by environmental friendly transition metal catalyzed living radical polymerization technique for use as additives for crude oils and petroleum products. The work paved the way for a) New processes for the development of tailor made polymeric additives and b)Development of additive formulations/ methodologies for transportation of high waxy crude oils as oil-in-water emulsion.

The major objectives of the proposed project was to develop technologies which could directly help in pollution abatement. The polymeric waste causes a major pollution, at the same time agro and agro-industrial wastes also cause pollution due to their disposal problems. If both these wastes can be utilized for production of high-value products, it will simultaneously serve as a new building construction material as well as an alternative substitute for wood. Wastes like paddy husk, banana plant fibre, rice straw, etc. and polymeric wastes like plastic wastes, carry bags, empty mineral bottles, etc. were evaluated and tested for their hardness, density, fibrous characteristics, etc. and their suitability for blending with polymeric binder were ascertained.

Standardization of different process parameters for preparation of natural dyes from waste flower and plant materials was carried out in the laboratory scale. To achieve the desired properties of the finished products testing were conducted as per BIS Standard to determine the yield, colour fastness and quality of dyes.

The complex tectonic model of the Shillong Plateau, the source area of the 1897 great earthquake in the North East India region was examined using the high precision data of a 20-station digital seismic network that is in operation in the Plateau since 2001. The dominating thrust/strike-slip faulting earthquakes in the Western Plateau although could be explained by the `pop-up’ tectonic model, the seismological data, however, showed that the north dipping Dapsi and the south dipping Brahmaputra faults are the possible boundary faults, not the Dauki and Oldham faults as were proposed in the model. The more intense normal/strike-slip faulting earthquakes in the eastern Plateau (Mikir massif), on the other hand, are generated by a long and deep rooted Kopili fault by transverse tectonics, and this could be more vulnerable source area for an impending large/great earthquake in the region. The study generated some seismological data which might be useful for earthquake prediction related studies. The work was published in Current Science, Vol 91, No.1, 10 July, 2006, pp-109-113 and appeared in fron page of the journal.

(i) About 400 earthquakes (M 3.4-5.7) recorded by a 21-station broadband seismic network during 2001-2004 were analysed to understand the complex tectonic model of the Shillong Plateau, the source area of the 1897 great earthquake in the northeast India region. Twenty six fault plane solutions are obtained by waveform inversion. The dominating thrust/strike-slip faulting earthquakes in the western Plateau although could be explained by the ‘pop-up’ tectonic model obtained by Geodetic/GPS observations [Bilham and England, 2001]; the seismological data suggest that the north dipping Dapsi and the south dipping Brahmaputra faults are the possible boundary faults, not the Dauki and Oldham faults as were proposed in the model. We further suggest that the Dhubri fault to the west and the Kopili fault to the east of the Plateau possibly accommodate the pop-up mechanism by strike slip movement. The intense normal/strike-slip faulting earthquakes in the eastern fragment of the Plateau (Mikir massif) are caused by the long and deep rooted Kopili fault by transverse tectonics, and this could be the more vulnerable source area for an impending large/great earthquake in the region.

(ii)Microearthquake spectra from Jubilee Hills, Hyderabad are analyzed to observe the effect of attenuation and site on these spectra. The ratios of spectral amplitudes at lower and higher frequency are measured for three different stations at varying epicentral distances to estimate Q value for both P- and S-wave in near and sub-surface layer. Average estimates of Qp and Qs are 235 and 278 respectively. Value of Qs/Qp larger than 1.0 suggest dry crust for most of the Jubilee hills region. The near-surface low Qp and Qs for 0 km to 0.9 km depth coincide with the soil layer, top and semi weathered and highly fractured zone. In contrast, at shallower depth beneath the Jubilee hills area, Hyderabad, we obtain high Qp and Qs zone, which correspond to the dense and high velocity rocks of the region. The varying corner frequencies for these spectra are inferred to be characteristics of site. Comparison of disparity in spectral content with reference to hard rock site conclude that lithology of the northwest part of Jubilee Hills area amplify about twice the incoming seismic signal, as compared with southern part best outlined at 8 to 10 Hz only.

In this study, 20-station digital seismic network data recorded during 2001 and 2003 in the Shillong Plateau region were analysed to understand the seismic model of the Plateau earthquakes. This network of seismic station was in full operation since 2001 by various institutes, like the National Geophysical Research Institute (NGRI), NEIST(earstwhile RRL)– Jorhat, Manipur University, Gauhati University etc. The network fairly covers the area of our interest to monitor the Shillong Plateau earthquakes. About 300 earthquakes (M > 2.0) were selected that were recorded by the digital network during the year 2001 and 2003. Out of these, high precision locations of 170 events were examined that are mostly located in the Plateau region inside the network, and a few located outside the network within a distance of about 100 km to the nearest station. These events are located by using the HYOPCENTER program of Linert et al. [1986] with an average rms 0.03 sec, epicenter and depth error < 1 km. An 1D inverted velocity model of Bhattacharya et al. [2002] was used to locate the events. The epicenter map is shown in Fig.1. The map shows two clusters of events,one at the Oldham /Brahmaputra fault zone at the northern boundary of the Plateau, and the other along the Kopili fault zone. 27 fault-plane solutions were determined, 17 by using the P-wave first motions and 10 by wave-form inversion; the solutions are also shown in Fig 1.

A north-south cross section of the events that occurred in the Shillong Plateau are examined across the Oldham/ Brahmaputra fault zone (Fig. 2); the considered events are shown by a shaded zone A-A' in Fig.1. Nine fault-plane solutions are obtained in the western Plateau region within the shaded zone A-A', the region is dominated by thrust/reverse faulting (Fig.1). Two more solutions were obtained (events 9 and 10) in the considered shaded zone (Fig.1); one in the Bengal basin that showed a strike slip faulting (event 9), and one in the Himalaya that showed a normal faulting (event 10). The strike-slip solution 9 may be correlated with the NE-SW trending Sylhet fault in the Bengal basin, and the normal solution 10 is possibly related to the Kopili fault that transversely extends into the Himalaya [Kayal, 2001; Bhattacharya et al., 2002]. The cross sections of the earthquakes and the fault-planes were examined with the proposed pop-up tectonic model (Fig.2). The program RAKE [Louvari and Kiratzi, 1997] was used to prepare the cross section of the fault planes. The dipping inferred fault planes of the nine solutions (events 1-8 and 27) that were obtained in the Plateau region and the fault planes of the events 9 and 10 were plotted at the respective depths in this section (Fig. 2).

Two cross-sections of the events were examined for the Kopili cluster, one NW-SE section along the Kopili fault, and one NE-SW section across the fault zone; the corresponding considered events are shown in the shaded zones B-B' and C-C' in Fig.1. A cross section of the fault planes of the 12 fault plane solutions, mostly normal and strike slip faulting, that were obtained for the considered cluster was also examined using the above RAKE software. All these sections are shown in Fig 3. In addition to these 12 fault-plane solutions (11, 13-23), (Fig.2), three fault plane solutions were obtained for the events (24-26) in the Indo-Burma ranges and one for the event 12 near the Dauki fault that occurred outside the shaded zone C-C' (Fig.1). The solution (event 12) near the Dauki fault showed a normal faulting. The Indo-Burma range earthquakes (events 24-26) showed dominantly thrust faulting with easterly/northeasterly dipping fault planes; these solutions may be attributed to the subduction tectonics as reported by many authors [e.g. Chen and Molnar, 1990; Kayal, 1996; Kumar and Rao, 1995].

The seismic activity in the western Shillong Plateau revealed that the activity below the Plateau is mostly confined down to a depth of 35 km (Fig 2b), and these events are bounded by the two boundary faults. Inference was, however, prefered to the north dipping Dapsi thrust (DT) as the southern boundary fault and the south dipping Brahmaputra fault (BF) as the northern boundary fault; these faults are responsible for generating the earthquakes in the western part of the Plateau, and the ‘pop-up’ tectonic model (Fig.2a) is conformable with our observations ( Fig 2b & c). The Dauki fault is a dominantly strike-slip/normal fault zone (Evans, 1964; Nandy, 2001), which is evident by a normal faulting solution (event 12) near the fault zone (Fig.1); although the nodal planes are not conformable with the E-W Dauki fault, but the tensional regime is evident. The fault-plane section fairly revealed the two boundary faults; the fault planes 1 and 2 reflect the north dipping Dapsi thrust, and the fault planes 5 and 27 reflect the south dipping Brahmaputra fault (Fig.1). We believe that the Dapsi thrust could be the southern boundary fault and the Brahmaputra fault could be the northern boundary fault for the ‘pop-up’ tectonic model. It may be noted that the event 9 occurred at a deeper depth (55 km) in the lower crust in Bengal basin where crustal thickness is much bigger compared to that of below the Shillong Plateau (Fig. 1).

In the Kopili fault zone the seismic activity is more intense, and base of the seismic zone extends down to 45 km (Fig.4a) . The cross section of the events across the fault zone shows two possible northeasterly dipping faults (Fig 4b). The cross-section of the fault planes at depth is fairly conformable with the two dipping faults, one being very prominent for the solutions 15,18 and 19, and the other is evident with the solution 23 and 16, though other complex fault-plane solutions exist in the zone. The entire Kopili fault zone is, however, dominated by normal/strike-slip faulting, unlike the thrust faulting earthquakes at the Dapsi/Brahmaputra fault zone in the western Plateau where ‘pop-up’ tectonics is dominated. The Kopili fault zone is believed to extend transversely below the Himalaya [Kayal, 2001; Bhattacharya et al., 2002]; this is also evident in this study; the solutions 10 and 16, that occurred to the north of Main Boundary Thrust (MBT) in the Himalaya (Fig.1), may be explained by this transverse seismogenic structure (Fig.1).

It was believed that these data of the digital seismic network shed new light in our understanding of the Shillong Plateau earthquakes. The ‘pop-up’ tectonic model is conformable with the seismic activity in the western Plateau, and we identify the DT and BF as the boundary faults for the pop-up tectonics. The Kopili fault zone earthquakes in the eastern Plateau, Mikir massif region, on the other hand, are different; these are caused by the long and deep rooted Kopili fault that is transversed to the Himalayan trend. Both the fault zones, the Dapsi/Brahmaputra and the Kopili fault zones, in the Shillong/Mikir Plateau are intensely active, but their tectonics are different. The Kopili zone is, however, more intensive with higher b-value and higher fractal dimension [Bhattacharya et al., 2002), and occurrence of an impending large earthquake was speculated in this zone.

Effect of attenuation and site on micro-earthquake spectra from Jubilee Hills, Hyderabad

Microearthquake spectra from Jubilee Hills, Hyderabad (Fig. 3) are analyzed to observe the effect of attenuation and site on these spectra. The ratios of spectral amplitudes at lower and higher frequency are measured for three different stations at varying epicentral distances to estimate Q value for both P- and S-wave in near and sub-surface layer.

The higher frequency content is supplementary in very nearby events. This observation suggested that the co-efficient of attenuation could be determined from the changes in spectral shape of earthquakes at very nearby distance from a fixed receiver. The spectra are determined for the first 0.4 sec of the P waves of the events. Travel time of P wave of the nearest event is 2.95 sec while distant event has the travel time of 4.51 sec. Nearer event is distinguished by reasonably higher spectral amplitude content than that obtained from distant event as viewed from the logarithmic amplitude scale along Y-axis. Particularly for these two earthquakes the spectral content shows variation in amplitude from 2Hz to approximately 28Hz. At frequency of 28Hz and beyond there is sharp fall in amplitude. Spectral amplitude in lower frequency range seems to vary between 6 to 10 Hz while for higher frequency range this is between 26 Hz to 30 Hz incase of most events. Hence the spectral amplitudes are anticipated by averaging the amplitude between 6 to 10 Hz and 26 Hz to 30 Hz to obtain the 8 Hz and 28 Hz spectral levels respectively. The spectral amplitude at 28 Hz relative to the amplitude at 8 Hz is much larger for nearest event than for the distant one. In the method of determining Q, two basic assumptions were made. Primarily it was assumed that Q is constant over the frequency band studied, 8 to 28 Hz. If Q is not constant in this band, then the Q values to be obtained in this study will represent a complicated average of the actual range of Q for these frequencies. The spectral shapes of these events between 8 and 28 Hz are to be identical at the earthquake source. Secondly it is also assumed that the source spectra of all the earthquakes in the study have the same values for the ratio of their 28 Hz/8 Hz amplitudes. The validity of this assumption can be tested by examining the scatter in the plots of spectral ratio against travel time. If the source spectra of events of similar travel times are significantly variable in the pass band, a difference in their spectral ratios should be apparent. The ratio of the spectral amplitude at 8 and 28 Hz has been observed for a number of earthquakes at different epicentral distances from all the three stations of the network. When the logarithms of the ratio are plotted against the travel time for the seismic waves, the slope of the data is proportional to 1/Q. The variation in Q due to scattering and the amplitude ratio depends on the shape of spectra invalidate the effect of geometrical spreading. The spectral amplitude of a body wave at frequency f is related to the travel time of seismic wave represented by

A(f) is dependent on the travel time of the seismic wave t and the source-receiver distance r. R(f) is the response function of the site to incoming seismic radiation. This transfer function basically imparts effects such as attenuation. For two different frequencies f1 and f2, the natural logarithm of their amplitude ratio is

If Ao(f1)/Ao(f2) and R(f1)/R(f2) are constant for all events under study and independent of travel time of the earthquakes used, then ln[A(f1)/A(f2)] plotted against t will have a slope of ?(f2-f1)/Q. In this study f1 is chosen at 28 Hz and f2 is 8 Hz. The slope contains the information about the attenuation and travel time of P and S. R(f1)/R(f2) will be constant for all of the earthquakes as long as the same station was used to determine the amplitude ratios and the site response is not a function of the azimuth or angle of incidence of the incoming seismic waves.

Qp and Qs are determined using events listed in Table -1. Vertical component seismograms are used for estimation of P-wave spectra. The spectral amplitudes ratios of the P-waves for these events are plotted as a function of P-wave travel time (tp) at station AOU. Logarithmic ratio of 28Hz amplitude / 8Hz amplitude decreases consistently with travel time for those events having P wave travel time greater than 2.8 sec. Simultaneously events having less than 2.8 sec P-wave travel time do not show any dependence with travel time. For this reason events having travel time greater than 2.8 sec are considered and yield a Qp of 179 for AOU.

Likewise, S-wave spectra are determined using the horizontal component seismograms. Events with S-wave travel times greater than 3.3 sec exhibit spectral ratios whose logarithms decrease with travel time. These events provide an estimate of Qs of 238, for travel times larger than 3.3 sec. However, earthquakes with S wave travel times less than 3.3 sec display amplitude ratios, which do not change notably with travel time. Qp and Qs estimated for AOU indicate that they are different for these paths. The y-intercepts of the lines that fit the data presented provide information on the differences in P and S wave spectra. This differences in the ratios extrapolated to zero travel time reflect variations of the spectra at the source and/or characteristics of the receiver site.

Similarly the spectral ratios of both P and S waves for the events recorded at station PSJ are studied as a function of travel time. The PSJ data yield a Qp of 179 using 32 events and a Qs of 209 from the ratio of same number of events. The logarithm of the y-intercept for the P-wave amplitude ratio at zero travel time is 1.5803. The logarithm of the S-wave amplitude ratio at zero travel time is calculated as 1.5816. This similarity in y intercepts between the P- and S-wave data signifies that the frequency content between P and S waves of similar travel times is a result of source effects only, not the site response. The average estimate of Qp and Qs from three stations are 235.5 and 278.8 respectively. In addition, to observe the variation of Q values with depth, the spectral ratios are calculated separately at two different thickness. First, the ratio is calculated for the soil layer, top and semi weathered and highly fractured zone ie. for 0 km upto the depth of 0.9km. Qp and Qs estimated for this formation are 225 and 148 respectively. Second, the ratios are observed for the events that occurred between the depth ranges of 0.9km to 2.8 km characterized by granite. It’s average Qp and Qs are 260 and 255 respectively. The increase in Qp and Qs is very much evident with reference to the increase in depth.

Although the epicenters are located very nearby the stations, it is implicit that the effect of crustal attenuation is relatively small. However effect of site are observed from the spectra of the same event at least for two different stations. Spectra at AOU and PSJ: examining the P-wave spectra at two different stations AOU and PSJ of the network indicates the implication of site effect. It is seen very clearly that spectra at AOU and PSJ that corner frequencies of the P-wave spectra observed at these two sites appear to be characteristics of the sites in spite of short epicentral distance. The differences in the corner frequencies may represent the varying rupture area at source. It may also be attributed to the varying lithology at the receiving site within these nearby stations. The higher corner frequencies at PSJ indicate heterogeneity beneath the station also seen in near surface litholog data (Krishnamurthy et. al., 2003). However the corner frequencies of S wave spectra for AOU and PSJ exhibit marginal difference. Consequently it is estimated that the errors in the estimation of the P-wave and S-wave corner frequencies are +4Hz and +2Hz respectively. Errors estimated are larger for P-wave corner frequencies because the higher frequencies are compressed on the logarithmic scale that is used when these spectra are displayed.

Differences in spectra of direct P and S wave along with respective scattered waves for an event, which is located within the network, are observed at PSJ station. The power spectra of the initial 0.2sec duration of the P-wave (the direct and scattered wave) exhibit a peak at about 37Hz. Following the P-direct wave the 1.30 sec duration of the S-wave (direct and scattered wave) spectra exhibits a peak at about 5Hz. The peak at corresponding frequency for S-wave clearly contains higher energy in comparison to that of direct P-wave spectra. The variations in maximum dominant frequency for the direct waves are inherited from the properties of the site and path.

An effort also has been made to study the disparity of the spectral content for records of local events, when the epicentral distance and the incident angle are practically the same for all the three stations. First we have selected PSJ as "Hard rock site ’’ by following Krishnamurthy et. al., 2003, Murthy et. al. 2004 and therefore is a reference station according to Steidl et al., 1996. The spectral ratios are calculated with respect to this station. The entire waveform is smoothed by linear regression to restrain some redundant signal exist in the raw waveform which in particular throw "artificial" enlargement to the spectral ratio. Event no. 34, 35, 36, 37, 38 as in Table 1 are used to observe spectral content. Emphasis is given to these events because of higher signal/noise ratio so that the waveforms are clear, free from noise. Only vertical component records are used. Five spectral ratios for AOU/PSJ are shown in Figure 5 together with an average spectral ratio out of these five events. Moderate dispersion of the spectral ratios is observed. The average spectral ratio so obtained is more or less stable. Fluctuation of average spectral ratio lies in the band of 1 to 3 Hz. Similarly Figure 5 shows the spectral ratio for PML/PSJ with five events along with their average spectral ratio. The deviation of average spectral ratio lies between 0.2 to 7.3 Hz i.e. not quite in the same band of oscillations of the average spectral ratio for AOU/PSJ. But on the contrary, the average spectral ratio PML/PSJ in Figure 6 has strong amplification (maximum of 2.3) at frequency around 9 Hz. Comparison of the average spectral ratio of AOU/PSJ (bold line) and PML/PSJ (thin line) can be seen in Figure 6. Figures 6a, 6b and 6c conclude that the geological structures of the northwest part of Jubilee Hills area amplify about twice the incoming seismic signal, as compared with southern part. This effect can be observed at 8 to 10 Hz only. No variation in average spectral ratio for AOU/PSJ and PML/PSJ could be seen within the range of 0.5 to 5 Hz. Variation beyond 5 Hz up to 10 Hz indicate characteristics of the site at northern and southern part of the region. As these events were from different directions, the average behavior of spectral ratio shows stronger dependence on the local site effect than on the directivity of the source.

We analyzed the spectra in order to estimate Qp and Qs based on the estimate of amplitude of the spectral content, corner frequency and travel time. Estimations of Qp, Qs, site induced corner frequencies and spectral ratio are made to evaluate the effects of site. Qp as estimated for AOU and PSJ are comparatively low while PML execute higher values of Qp and Qs. While correlating rock type with Q, average Qp and Qs value exhibit availability of the hard granitic rock in the region. Average Qs obtained for AOU, PSJ and PML are higher than average Qp with Qs~1.33Qp. As a matter of fact Qp/Qs provide an important constraint for attenuation mechanisms. Rautian et. al(1978) reports that Qs is observed to be larger than Qp for paths in the crust near Garm, Tadjikistan so that tsQs-1~ tpQp-1 . Notably this is reflected in our observation that Qs ~1.33Qp. Possibly this variation is attributable to attenuation mechanism for the associated crustal path. The value of Qs/Qp larger than 1.0 suggest dry crust for most of the Jubilee Hills region. Low Qp and Qs are obtained for 0 km down to 0.9 km depth whereas events greater than 0.9 km depth upto 2.8 km exhibit higher values of Qp and Qs. Generally Qp and Qs increase rapidly with depth. In contrast, at shallower depth beneath the Jubilee Hills area, Hyderabad , we obtain high Qp and Qs zone, which correspond to the dense and high velocity rocks of the region. A clear transition zones of varying Qp and Qs connects regions of high and low Qp and Qs. Since all the stations are separated not too far, the maximum distance is 700 meter (radius), the variation of Qp and Qs is obviously caused by the site effect near the station only. In addition while observing the spectral amplitude ratio of the nearby events, it is different with respect to the travel time. This differences in the travel time ratios when extrapolated to zero reflect response of the receiver site. The P-wave corner frequencies for the events at these stations vary between 18 to 24 Hz whereas S-wave corner frequency ranges from 14 to 16Hz. Thus the non-uniformity of P-wave corner frequencies observed at AOU and PSJ indicates that the corner frequencies of the source spectra of these earthquakes may be covered by the function of the receiving site. The differences in the P-wave spectra are enriched by higher mode frequency in comparison to S-wave; on the contrary P-wave spectra appear to decrease rapidly at frequencies higher than corner frequencies. In case of S wave spectra, the decrease is relatively gradual. These observations generally relate the rupture process only.

There appear to be feeble considerable between the spectral ratio at the frequency range of 0.5 to 5.0 Hz and the near and sub-surface lithology of the area in which the recording stations are located. The correlation can be observed in the range of frequency 5 to 10 Hz where northwest part of Jubilee hills area amplify about twice the impending signal, as compared with southern part at frequency range from 8 to 10 Hz. In an all probably due to the presence of soil, weathered and fractured zone underneath the site of station PML, the seismic signal in a moderately narrow band, is amplified further as compared with the site of station AOU. Thus this is the total effect of soil and fractured zone underneath. Quantification of the above results at several locations with proper litholog information would facilitate a detailed investigation.

(i) Seismotectonics and the current state of stress in Chedrang valley and its vicinity – the rupture area of Great Assam earthquake of June 12, 1897 (M=8.7) from waveform and stress tensor inversion.

The seismotectonics and the current state of stress for Chedrang valley and its vicinity, Shillong plateau, the rupture area of Great Assam earthquake of 1897 in northeastern region are observed with the help of high precision seismicity data during the period 1982-2003. Since the detailed picture of seismicity of chedrang fault and its vicinity is not known, an effort is made to investigate its seismotectonics for deciphering the seismicity, seismogenic zone and the prevailing stress pattern in the region. The seismicity pattern indicates that epicenters align along with Dudhnoi, Chedrang and Samin faults for the earth tremors of magnitude 1.0-4.0, 2.1-5.0 and 2.1-4.0 respectively and the micro tremor activity is relatively more intense towards the east of Chedrang fault than its western part. Absence of seismic activity is observed in association with Dapsi reverse and dauki faults. Since the maximum number of shocks within the depth interval 0 -30km is more than the number of shocks in the depth interval 30 - 50km, the bottom of seismogenic zone is inferred to be at 30km. Simultaneously, rupture process of associated faults are observed by determining the 9 focal mechanism solutions through waveform inversion incorporating the empirical Green’s function besides 5 solutions by using P-wave first motions. The solutions are mostly thrust and strike slip type mechanism with an exception of an event as oblique mechanism. One of these mechanisms suggests thrust faulting with a significant portion of strike-slip motion and the associated fault i.e. Chedrang fault dips towards north of northeast. The stress tensor inversion from 14 mechanisms suggests that the region is characterized by NNW-SSE compression in Chedrang valley and its vicinity with predominant thrust faulting. Sudden change of stress regime from prevailing NNE to NNW is indication of probable occurrence of a large earthquake.

(ii)A seismological database for Assam syntax zone during the period 1950-2006 has been prepared for b-values studies. The database is a collation of inputs from various National and International agencies. The database is also supplemented by the focal mechanism solution inferred already.

Estimation of crustal discontinuities using digital seismic waves in Shillong - Mikir Plateau of

The eastern extension of the Himalaya covers most parts of the northeastern region (NER) of India. The complexity in geotectonic setup poses the NER to be one of the most active seismic zones in the world. The seismic activity of NER is well reflected by occurrences of two great earthquakes, the June 12, 1897 (Ms 8.7) and the August 15, 1950 (Ms 8.7) earthquakes, and about 20 large M > 7.0 earthquakes during the last 100 + years since the great 1897 event in the Shillong-Mikir Plateau. The seismicity and the epicentral tract are the subject of several studies. (eg. Kayal et. al. 1987, Baruah et. al. 1997, Mukhopadhayay et. al. 1997, Chen and Molnar 1990 and Rajendran et. al., 2004 ). The NER is over thrust at the eastern Himalaya to the north and at the Indo-Burma ranges to the east, which cause pop-up tectonics in the Shillong- Mikir plateau (Bilham and England, 2001). Crustal structure/discontinuities play a major role to understand seismotectonics of a region. In this study an attempt is made to shed light on the Conrad discontinuity, the discontinuity between the upper and lower crust, and on the Mohorovicic (Moho) discontinuity, the discontinuity between the lower crust and the upper mantle. The NER is now well equipped with about 20 broadband (BB) seismic stations since 2001 to monitor seismic activity and to understand the earthquake generating process in this tectonically complex region. The BB seismic data have been very useful for high precision location (epicenter and focal depth) of the recorded events using the first P and S arrivals, and also for the fault plane solutions of the events in the region (Kayal et al., 2006). The digital waveforms of the seismic events, however, make it also possible for precise detection of the seismic phases that are reflected, refracted and converted at the crustal discontinuities. Conrad discontinuity may be estimated using the reflected P and S waves, denoted as PxP and SxS, that are produced a critical distance ranges. Similarly, the P and S waves are also reflected at the Moho, denoted as PmP and SmS. The observed travel time of these phases may be matched with the theoretical travel time for evaluating the crustal discontinuities. The work was undertaken as a Ph D desertation programme.

Estimation of amplitude frequency response and background noise evaluation of the digital

A methodology is attempted to determine the amplitude frequency response information and evaluation of background noise condition of the digital seismograph stations in northeast India. Basically the concept of the frequency response function, the ratio of Fourier transform of the output signal to the Fourier transform of the input signal, is adopted. The signal is convolved with the transfer function for different seismometers. Estimation of amplitude frequency response to the ground velocity with known pole-zero distribution ascertains the usable frequency band. It is observed that the 0.003 – 3 Hz is the passband for the seismograph stations equipped with Reftek 72A–08 (digitizer) and CMG-3T (seismometer) for 120 sec period, 0.02-11Hz for the Reftek 72A–08 and CMG-3ESP at 60sec period, while the passband is found to be 0.01 - 4.0 Hz for the Reftek 72A–08 and CMG-40T for 30 sec. Signal beyond these bands are sharply attenuated. The plateau value (i.e. the amplitude value within the passband) is marginally above 1.0 counts/nm/sec. The evaluation of background noise is of each seismic station is also done estimating the power spectrum using the algorithm LMN (Paterson, 1993). The station noise characteristics are revealed by this study.

Seismological data base has been prepared for about 1776 earthquakes in Chedrang valley and its vicinity, East Garo Hills, Meghalaya during the period 2004-2005. The database is useful to the assessment of seismic hazard in the Chedrang valley region in Meghalaya.

Under the project three component digital broadband seismograph stations at several places of Assam, Nagaland, Arunachal Pradesh and Meghalaya were established. The project was funded by Department of Science & Technology, Govt. of India, New Delhi.